I personally am using an XFX 650w on my quad quad (8354 procs, currently only 4x2gb ram, 8800GT)
max load i've seen on it *running non stop pi calcs* has been ~400w at the UPS, don't have more precise for 2 reasons
1) not at home right now
2) system was using shared load off my UPS

I'm aware of the difference between pcie 8pin connectors and eps12v connectors. In my previous post I was talking about eps12v 8-pins, not pcie 8pin connectors - sorry for any confusion this may have caused. I'm not willing to buy two power supplies for this. I'm gonna give tyan a call and see if I even need to power the 4pin. If I have to I guess I'll just get one of these:

I think (could be wrong) that all of the gang here that's built S4985based systems have just ended up powering them all- if you'd like, i could (when I get home) try firing mine up without the P4 block powered (I have mine 2x8pin eps, 4pin, molex) and ill report back

I'd really appreciate that, unless you feel it could harm your system or anything.
I think I'll just get an Enermax SGalaxy Evo 1250w power supply, I just spent some time looking and it and it's amazing.